libnvdimm, pmem: fix persistence warning

The pmem driver assumes if platform firmware describes the memory
devices associated with a persistent memory range and
CONFIG_ARCH_HAS_PMEM_API=y that it has all the mechanism necessary to
flush data to a power-fail safe zone. We warn if the firmware does not
describe memory devices, but we also need to warn if the architecture
does not claim pmem support.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 3c06a6e..41b4cdf 100644 (file)
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1037,8 +1037,9 @@ int nvdimm_has_flush(struct nd_region *nd_region)
 {
        int i;
 
-       /* no nvdimm == flushing capability unknown */
-       if (nd_region->ndr_mappings == 0)
+       /* no nvdimm or pmem api == flushing capability unknown */
+       if (nd_region->ndr_mappings == 0
+                       || !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
                return -ENXIO;
 
        for (i = 0; i < nd_region->ndr_mappings; i++) {